1. Field of the Invention
This invention relates to a process for forming fine patterns with a negative resist suitable for fabrication of semiconductors, magnetic bubble elements, light applied components and the like.
2. Description of the Prior Art
Recently there have been increasing severe demands for high integration of semiconductor integrated circuits and the like. In this connection, light having shorter wavelength than that of conventional one (particularly, ultraviolet rays) such as electron beam, X-rays, far ultraviolet rays or the like has been utilized in place of such conventional light in the field of lithography.
Especially, the lithographic technique wherein such far ultraviolet rays as mentioned above are utilized is not only extension technique of conventional photolithography, but also a technique wherein submicron transfer becomes easily possible. Thus, such lithographic technique may be much expected for future fine workings. These fine workings may be classified into etching method and lift-off method.
In case of lift-off method, severe conditions such as a suitable profile in resist film, thermal resistance, solubility, adhesive properties and the like are required in respect of a resist to be used. More specifically, it is necessary for easy pattern formation in accordance with lift-off method that a layer applied on the resist film can easily be removed together with solution of the resist. For this reason, it is required that a profile of the resist film patterned must be in overhung form.
In order to obtain such overhung form, either a means for forming a multi-layer construction of resist, or a means for treating a positive type photoresist, e.g., AZ-1350J (trade name of photoresist manufactured by Shipley Co.) with chlorobenzene is adopted at present. However, these means are complicated and inferior in the throughput, and the reproducibility thereof is not necessarily favorable.